What is the treatment for hypernatremia (elevated sodium levels)?

Treatment of Hypernatremia

The treatment of hypernatremia requires careful administration of hypotonic fluids to correct the free water deficit while avoiding overly rapid correction, with a maximum sodium reduction rate of 8-10 mmol/L per day for chronic hypernatremia. 1

Diagnostic Approach

Before initiating treatment, proper assessment is essential:

1. Confirm true hypernatremia (serum sodium >145 mEq/L)
2. Assess volume status (hypovolemic, euvolemic, or hypervolemic)
3. Determine duration (acute <48 hours vs. chronic >48 hours)
4. Evaluate underlying cause:
   • Inadequate water intake
   • Excessive water loss (renal or extrarenal)
   • Excessive sodium intake

Treatment Algorithm

Step 1: Calculate Free Water Deficit

Calculate the free water deficit using the formula:

• Free water deficit = Total body water × [(Current Na⁺/140) - 1]
• Total body water ≈ 0.6 × weight (kg) for men; 0.5 × weight (kg) for women

Step 2: Determine Rate of Correction

• For acute hypernatremia (<48 hours): Can correct more rapidly, even within 24 hours 1
• For chronic hypernatremia (>48 hours): Correct at maximum rate of 8-10 mmol/L/day 1, 2

Step 3: Choose Appropriate Fluid

Selection based on volume status:

For Hypovolemic Hypernatremia:

• Initial phase: Normal saline (0.9% NaCl) to restore hemodynamic stability
• Maintenance phase: Switch to hypotonic solutions (0.45% NaCl or 5% dextrose) 3, 2

For Euvolemic Hypernatremia:

• 5% Dextrose in water (D5W)
• 0.45% NaCl (half-normal saline) 3, 2

For Hypervolemic Hypernatremia:

• Loop diuretics to promote free water retention and sodium excretion
• Hypotonic fluids as needed 4, 2

Step 4: Special Considerations

• For diabetes insipidus: Consider desmopressin (DDAVP) administration 1, 2
• For severe cases: Hemodialysis may be considered for acute, severe hypernatremia 1

Monitoring and Adjustments

• Check serum sodium every 4-6 hours during active correction
• Adjust fluid rate based on sodium measurements
• Monitor for signs of cerebral edema (headache, altered mental status, seizures)
• Assess fluid balance and hemodynamic parameters regularly

Pitfalls to Avoid

1. Overly rapid correction: Can lead to cerebral edema, especially in chronic hypernatremia
2. Inadequate monitoring: Failure to check sodium levels frequently during correction
3. Inappropriate fluid selection: Using isotonic fluids when hypotonic fluids are needed
4. Overlooking ongoing losses: Not accounting for continued water losses during treatment
5. Failure to treat underlying cause: Not addressing the primary etiology of hypernatremia

Special Populations

• Elderly patients: Often have impaired thirst mechanisms and require closer monitoring
• ICU patients: At higher risk due to inability to access free water and increased insensible losses 4
• Patients with renal failure: May require modified approaches to fluid management

Remember that hypernatremia represents a deficit of free water relative to sodium, and treatment should focus on careful replacement of this deficit while addressing the underlying cause.